Prevalence and trends in overactive bladder among men in the United States, 2005–2020

The purpose of present study was to examine the current prevalence and recent trends of overactive bladder (OAB) among US adult men and examine the correlations between OAB and several potential risk factors. The study used the nationally representative data between 2005 and 2020 from the National Health and Nutrition Examination Survey in the US. A total of 18,386 participants aged ≥ 20 years were included in the study. We divided the data into three groups: 2005–2008, 2009–2014 and 2015–2020 to investigate the trends in OAB prevalence. The weighted prevalence and corresponding 95% confidence intervals (CI) of OAB were calculated. The differences (95% CI) in prevalence between the surveys were calculated and multivariate-adjusted weighted logistic regression analysis was performed to determine the correlates of OAB. Among all US adult men, the overall prevalence of OAB increased slightly from 11.3% in 2005–2008 to 11.7% in 2009–2014 and significantly increased to 14.5% in 2015–2020 (difference, 3.2% [95% CI (1.9–4.4%)]; P < 0.05). Increases in OAB prevalence especially concentrated on those who were 40–59 years, non-Hispanic White, non-Hispanic Black and those who were overweight and obese. Older age, non-Hispanic Black, lower educational level and family poverty ratio, diabetes, depression, sleep disorder, other chronic comorbidities, less intense recreational activity, poorer health condition and unsafe food were independent risk factors of OAB. The contemporary prevalence of OAB was high, affecting 14.5% US men and the estimated overall prevalence significantly increased from 2005 to 2020. Therefore, future research should be focused to prevent and remedy this growing socioeconomic and individually troublesome malady.


Assessment and definitions of OAB
The data on OAB associated symptoms including UUI and nocturia were collected by using Kidney Conditions-Urology (KIQ_U) questionnaire in the mobile examination center (MEC).Two questions were asked to assess the severity of UUI: 1. "During the past 12 months, have you leaked or lost control of even a small amount of urine with an urge or pressure to urinate and you couldn't get to the toilet fast enough?" 2. "How frequently does this occur?"And another question was asked to assess the severity of nocturia: "During the past 30 days, how many times per night did you most typically get up to urinate, from the time you went to bed at night until the time you got up in the morning?".
To further identify OAB, we used the established OABSS questionnaire developed by Blaivas et al. 14 The method for conversion of NHANES symptom frequencies to OABSS are shown in Table 1.Finally, we combined the UUI score and nocturia score and total score of ≥ 3 indicated a diagnosis of OAB disorder.

Statistical analysis
Statistical analysis was performed with R version 4. Estimates on weighted overall prevalence (95% confidence interval (CI)) of OAB were calculated in each survey and were further calculated by age group, race/ethnicity group and BMI group.The differences (95% CI) of prevalence between the surveys were calculated and were considered to be statistically significant if χ 2 test had a P value of less than 0.05.To perform the multiple logistic regression analysis, we tested the multicollinearity of independent variables and found no multicollinearity in these variables.In addition, the sample size was enough to conduct the multiple logistic regression analysis.Thus, weighted logistic regressions were used to explore the correlates of OAB by incorporating age, race/ethnicity, education, family poverty ratio, body mass index, smoking, hypertension, diabetes, depression, sleep time, sleep disorder, chronic conditions, recreational activity, diet, health condition, food security and health insurance.All statistical tests were 2 sided, with P < 0.05 considered statistically significant.

Participant characteristics
Of the 76,496 individuals who participated in NHANES from 2005 to 2020, we excluded 33,084 participants who were younger than 20 years, 22,385 who were women, and 2641 who had incomplete information of UUI and/ or nocturia.The final study population included 18,386 male adults aged ≥ 20 years and who had complete data.
There was no significant difference of the most variables including age and race/ethnicity composition between the three surveys.Detailed data on demographic characteristics and other participants' features in each survey were shown in Table 2.

Discussion
Data on the epidemiology of male OAB are scarce.About two decades ago, the National Overactive Bladder Evaluation (NOBLE) program was performed to investigate the overall prevalence and burden of OAB in the US and reported an overall prevalence of 16.0% for US men in 2002 15 using clinically validated computer-assisted telephone interview (CATI) questionnaire which was different from OABSS.Another study published in 2013 reported the prevalence of OAB defined by the presence of urinary urgency ≥ ''often,'' and/or the presence of UUI was around 8% in US men 5 .The difference in OAB prevalence between our study and previous studies may be related to the method of epidemiological investigation, study designs, different OAB definitions, response rates, and study population.The contemporary prevalence and recent trends in male OAB were unknown.The present study, for the first time, systematically evaluated nearly 20-year trend in OAB among US men.Although two prior studies that revealed the overall incidence of UUI increased significantly from 2005 to 2018 16 and the overall incidence of nocturia increased significantly from 2005 to 2016 17 in US men, the authors did not evaluate the prevalence of OAB, thus the increasing trends in UUI and nocturia may be attributed to the increasing OAB prevalence.
The reason and mechanism of increasing OAB prevalence remained unclear, it may not because of the increase in aging population, as we did not observe the increasing trend of OAB prevalence in those aged ≥ 60 years.Additionally, although we found a significant increase in non-Hispanic Black men, the proportion of Black men Vol:.( 1234567890 www.nature.com/scientificreports/did not increase across the three surveys.Although obese persons seemed to be increasing and an increasing trend was observed in obese men, we failed to demonstrate an independent association of obesity and OAB.Nevertheless, neurological disorders, particularly Parkinson disease and multiple sclerosis, and antidepressant use are potential causes of OAB, and are increasing in the US in recent years [18][19][20] .Therefore, future study should be focused to explore the reasons why OAB prevalence increased.The prevalence and trends of OAB were found to be associated with some sociodemographic features.Non-Hispanic Black men had a higher prevalence of OAB, this was consistent with the results of a racially diverse population study 21 .Moreover, a significant increase trend was observed in non-Hispanic Black men in our study.However, the specific reasons for racial differences in OAB remained unclear, they were likely multifactorial.OAB is commonly found in men diagnosed with benign prostatic hyperplasia (BPH) and/or an enlarged prostate.The risk of developing BPH is significantly higher among non-Hispanic Black and Hispanic men compared to non-Hispanic White men 22,23 .Furthermore, racial minorities in the US tend to have lower educational levels, engage in physically demanding jobs, earn lower incomes, and experience higher stress levels.These factors have been associated with an increased risk of urinary system diseases 24,25 .Additionally, the reason that a higher educational level and family poverty ratio had a lower prevalence of OAB 6,10,15 may be attributed to the fact those people tend to have better health-seeking behaviors and adopt healthier lifestyles.Conversely, individuals with lower education and income levels may have a higher prevalence of smoking, poor diet, increased physical labor, and exposure to toxins, which increases their susceptibility to developing OAB.www.nature.com/scientificreports/Chronic comorbidities, diabetes, stroke or cancer, were all associated with a higher prevalence with OAB, probably by compromising pelvic floor vascular, nerve and muscle function [26][27][28] .Stroke, diabetes and cancer may cause neurological conditions such as central nerve system injury and diabetic autonomic neuropathy, which may lead to the occurrence of OAB 29 .Additionally, depression and sleep disorder were associated with a higher prevalence of OAB in our study.Previous studies demonstrated that OAB or its associated symptoms such as nocturia may result in poor sleep and sleep apnea 30,31 , and mental health conditions such as anxiety and   32 .In fact, sleep or mental problems and OAB may be causal to each other, OAB can obviously affect mental health and sleep quality and sleep disorder or mental problems such as anxiety and depression, in turn, affect and aggravate the condition of OAB, which may be related to the dysregulation of bladder function by numerous neural pathways.Additionally, this analysis found that those who had a vigorous recreational activity, good health condition and good food security had a lower risk of experiencing OAB.Therefore, these healthy lifestyles are recommended in daily life to prevent the occurrence of OAB and relieve or manage OAB.
The NHANES design constituted the principal strengths of this study.NHANES employed a sophisticated multistage, probability-based sampling procedure to enroll a sample that properly represented the overall United States population.Furthermore, standardized protocols ensured the quality of data collection in NHANES.However, this study had some limitations, such as the fact that confirmation of OAB relied on self-reported information with no comprehensive clinical examination, including physical assessment, urine analysis, ultrasound, or urodynamic testing.Additionally, recall biases could have influenced the self-reported data used in the study.Due to the cross-sectional nature of the study, it was not possible to capture newly developed cases of OAB or assess the duration of OAB.Finally, the noninstitutionalized nature of participants included in the study implied that the actual prevalence of OAB may have been underestimated since individuals in hospitals or nursing homes were not represented.However, the present study provided crucial observations of contemporary epidemiology of OAB, and disparities of OAB in sociodemographic, comorbidities and lifestyles, which may inform future studies and public health planning.

Conclusions
The contemporary prevalence of OAB was high, affecting 14.5% US men.The overall prevalence of OAB significantly increased across recent two decades, especially among men who were aged 40-59 years, non-Hispanic White and Black, and overweight and obese men.Future studies are needed to address OAB disparities across sociodemographic subgroups and to investigate the factors driving the rising trends in subtypes of OAB among older men, non-Hispanic White and Black, and obese men.Focused research can help prevent and remedy this growing socioeconomic and individually troublesome malady.

Table 3 .
Weighted trends in OAB prevalence among US men, NHANES 2005 to 2020.Data were expressed as % (95% CI).OAB, overactive bladder; NHANES, National Health and Nutrition Examination Survey; BMI, body mass index; CI, confidence interval.a All estimates were weighted to be nationally representative.b The difference of OAB prevalence between 2005-2008 and 2009-2014, a negative value indicates a decrease in the prevalence between the two time periods .c The difference of OAB prevalence between 2009-2014 and 2015-2020, a negative value indicates a decrease in the prevalence between the two time periods.d Total difference means the difference between 2015-2020 and 2005-2008.*P < 0.05.https://doi.org/10.1038/s41598-024-66758-8

Table 2 .
Baseline characteristics of the study population in the NHANES, 2005 to 2020.Data were expressed as %.NHANES National Health and Nutrition Examination Survey, BMI body mass index.a All estimates were weighted to be nationally representative.No. of participants for some variables may not sum up to equal the unweighted and weighted number due to missing data.b "Other" includes race and ethnicity other than non-Hispanic White, non-Hispanic Black, and Hispanic, including multiracial.c Chronic diseases included asthma, arthritis, congestive heart failure, coronary heart disease, angina/angina pectoris, heart attack, stroke, thyroid problem, any liver condition and cancer.

Table 4 .
Weighted logistic regression models of OAB among men, NHANES 2005 to 2020.OAB, overactive bladder; NHANES, National Health and Nutrition Examination Survey; OR, odds ratio; CI, confidence interval; BMI, body mass index.a All estimates were weighted to be nationally representative.b Chronic diseases included asthma, arthritis, congestive heart failure, coronary heart disease, angina/angina pectoris, heart attack, stroke, thyroid problem, any liver condition and cancer.